CA1065530A - Flame retardant rigid polyurethane syntactic foam - Google Patents

Flame retardant rigid polyurethane syntactic foam

Info

Publication number
CA1065530A
CA1065530A CA251,056A CA251056A CA1065530A CA 1065530 A CA1065530 A CA 1065530A CA 251056 A CA251056 A CA 251056A CA 1065530 A CA1065530 A CA 1065530A
Authority
CA
Canada
Prior art keywords
mixture
flame retardant
rigid polyurethane
foam
polyisocyanate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA251,056A
Other languages
French (fr)
Inventor
Jack R. Harper
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dow Silicones Corp
Original Assignee
Dow Corning Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US05/662,384 external-priority patent/US4082702A/en
Application filed by Dow Corning Corp filed Critical Dow Corning Corp
Application granted granted Critical
Publication of CA1065530A publication Critical patent/CA1065530A/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00Polymeric products of isocyanates or isothiocyanates
    • C08G18/06Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40High-molecular-weight compounds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/32Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof from compositions containing microballoons, e.g. syntactic foams
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2110/00Foam properties
    • C08G2110/0025Foam properties rigid
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2375/00Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
    • C08J2375/04Polyurethanes

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Polyurethanes Or Polyureas (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

A rigid polyurethane syntactic foam is obtained by mixing an organic polyol, a polyisocyanate, a catalyst for the reaction of the polyol and polyisocyanate, microballons and a flame retardant. The foam is useful for structural purposes as a replacement for wood.

Description

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This invention relates to a flame retardant rigid polyurethane syntactic foam.
Compositions which contain hollow beads, bubbles or microballoons have been known for many years. The concept of using these hollow beads in a composition is designed to reduce the density and also reduce the high cost of the matrix material. It was observed, however, that a reduction in density also resulted in a reduction of the structural strength of the product and it was difficult to retain maximum strength with reduced density.
From the prior art, it is well known to use liquid reactants to make polyurethanes, both foams and solid products. It is also well known that flame retardants, such as tris(2-chloroethyl)phosphate can be used in polyurethanes as a flame retardant. It is also apparent from the prior art that if such a flame retardant material is used there are too many disadvantages associated with this low molecular weight material to be broadly useful in making flame retardant polyurethane foams. It is also known from the prior art to use solvents or diluents for compositions which contain large amounts of microballoons. However, it has not been known heretofore that a rigid polyurethane syntactic foam could be made which is pourable or castable, have a relatively low density, contain a large amount of micro-balloons, cures to a product which is structurally as strong as wood or stronger, could be cast and cured in thick section and ha~e a flame retardant property which exceeds prior art rigid polyurethanes.

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~8t;;SS30 This invention relates to a flame retardant rigid polyurethane syntactic foam which is made from a mixture of microballoons, an organic polyol, a polyisocyanate, a catalyst and a flame retardant which also acts as a flow promoter.
The flame retardant provides the composition with sufficient fluidity to allow it to be cast into molds, flow into crevices to duplicate mold detail and provides composition which when cured will be flame retardant and structurally strong. The flexural strength can be improved by adding to the mixture noncombustible flexible fibers, such as glass fibers. The composition cures in large molds and will provide a cured product which can be substituted for wood with the added advantage that it is flame retardant.
It is therefore an object of this invention to provide a flame retardant syntactic foam which can be cast in a mold and cures to a product which is a substitute for wood and is also flame retardant. These and other ob~ects will become more apparent in the following detailed discussion.
This invention relates to a rigid polyurethane syntactic foam consisting of a cured product obtained from a mixture consisting essentially of the composition obtained by mixing an organic polyol, a polyisocyanate, microballoons, a catalyst for the reaction between the organic polyol and polyisocyanate, and a substantially colorless, compatible flame retardant having a viscosity less than 100 centipoise at 24C., having a volatility such that the flame retardant does not evaporate from the exotherm generated by reacting ingredients and said flame retardant is non-reactive in the mixture to ~ SS 30 the extent that the physical properties of the :Eoam are not substantially changed compared to the physical properties of the foam ~ithout the :Elame retardant presenk J a combination of the organic polyol and the poly.isocyanate being a liquid at 25C., there being present in the mixture a su~ficient amount of micro-balloons to provide a non-castable mixture in the absence of the flame retardant and the amount of flame retardant present in the mixture being sufficient to provide a castable mixture which will flow in a mold cavity to the extent that mold details are filled, and the mixture cures to a rlgid polyurethane syntactic foam which is flame retardant.
The organic p~lyols and polyisocyanates which are liquids at 25C. are well known in the prior art. The specific polyQls or isocyanates are not critical except that a combination of the two are liquid at 25C. The organic polyol can be either of the polyether type or the polyester type. It is also w:ithin the scope of this in~ention to use some prereacted combinations of organic polyol and polyisocyanate. The organic polyol and poly-isocyanate, however, are those combinations of organic polyol and polyisocyanate which gi~e rigid polyurethane.
The microb~lloons can be made from any material known in the art, but are preferably made from glass which provides the optimum physical properties for strength The particle size of the microballoons are those ~rdinarily found in the prior art.

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The catalysts are those conventionally used to cure polyurethanes, especially those which catalyze the reaction between organic polyols and polyisocyanate, such as amines and tin catalyst.
The flame retardants suitable for the rigid polyurethane syntactic foams of th~s invention are those which have a viscosity of less than 100 centipoise at 24C. Flame retardants which are solids or have viscosities greater than 100 centipoise at 24C. do not provide all the properties of the mixture as well as of the cured foam, however, small amounts of these other flame retardants can be used with the low viscosity flame retardants for some additional benefits but their amounts should not interfere with the overall property profile of the mixture or cured foam. The flame retardant should also be compatible with the polyurethane reactants and with the cured foam to the extent that it does not exude from the cured foam or separate from the mixture. The volatility of the flame retardant must be sufficiently high so that it does not evaporate from the mixture during the exotherm generated by the reacting ingredients. The flame retardant should also be non-reactive in the mixture to the extent that the physical properties of the cured syntactic foam are not substantially changed compared to the physical properties of the cured syntactic foam without the flame retardant present. The preferred flameIretardant is tris(betachloroethyl)phosphate~
A foam with a combination of properties of low density, strength, fluidity and flame retardancy result from using liquid organic polyol and polyisocyanate combinations and using a sufficient amount of microballoons S5~3 to make the resulting mixture non-castable, non-flo~ing and then using enough flame retardant as described above to make the mixture castable to the extent that ~t will flow in a mold cavity such that the mold details are filled. By using these amounts, the resulting cured rigicl polyurethane syntactic foam is strong, low in density and flame retardant.
The amounts of each ingredient will depend upon the particular organic polyol, polyisocyanate and microballoon used. These ingredients vary broadly in characteristics and thus the amount of each will vary likewise. The relative amounts of organic polyol and polyisocyanate are used in the stoichiometric amounts of the prior art.
The mixture can also contain noncombustible flexible fibers which are less than 25 mm in length.
These noncombustible flexible fibers improve the flexural strength of the rigid polyurethane syntactic foam. A
preferred noncombustible flexible fiber is glass fiber.
These noncombustible flexible fibers can be a single monofilament or fiber of multi-filament which are herein referred to as bundles. The fibers can be chopped into the desired lengths from longer strands. Preferably, the fibers are about 6 mm in length. These noncombustible fibers improve the flexural strength of the rigid polyurethane syntactic fo~m without disturbing the flame retardant properties or the casting properties of the mixture.
The amount of noncombustible flexible fiber will vary in accordance with the particular mixing and molding equipment available. The amount should not be such that it reduces the fluidity of the mixture to a point where the mixture is no longer suitable for casting into a mold.

~J

~ S5 ~ ~

Amounts of from 5 to 15 weight percent based on the total weight of the mixture have been ound suitable to increase the flexural strength without reducing the ability of the mixture to be cast into a mold.
The ingredients are combined in the manner usually used in the prior art in that the polyisocyanate is usually added last. Any other method of combining the ingredients is applicable as long as the final mixture can be cast into a mold. ~nce all the ingredients are combined, the mixture will cure at room temperature to a rigid polyurethane synt~ctic foam.
The syntactic foams of this invention are suitable for structural purposes, such as a replacement for wood and have the added advantage of being flame retardant.
The following examples are presented for illustrative purposes only and should not be construed as limiting the invention which is properly delineated in the claims.
Example 1 A mixture of 6 parts by weight of a commercial organic polyol ~Voranol RS-350, trademarked and sold by Dow Chemical Company), 6 parts by weight of polymethylene polyphenyldi-isocyanate, 6 parts by weight of tris~betachloroethyl)-phosphate, 2.5 parts of glass microballoons and 0.1 part by weight of a mixture of 1 part by weight of triethylene diamine and 2 parts by weight of dipropylene glycol was prepared. The above mixture was prepared by adding the isocyanate ingredient last. The resulting mixture was fluid and could readily be cast into a mold and when cured to a rigid polyurethane syntactic foam, was non-burning.
A mixture was prepared as described above except the ,~

~ ~ 5 S ~ ~

tris~betachloroethyl)phosphate was let out. This mixture was a wet powder, was not castable and when cured, burned.
This mat0rial had a limiting oxygen index ~LOI) o-f 17% oxygen whereas the mixture containing the tris(betachloroethyl)-phosphate had an LOI of 80~ oxygen.
Example 2 A mixture o 100 parts by weight of the commercial organic polyol employed in ~xample 1, 42 parts by weight glass microballoons, 75 parts by weight of tris(betachloroethyl)-phosphate, 1 part by weight of the catalyst mixture of Example 1,and 100 parts by weight of polymethylene polyphenyl diisocyanate was prepared by adding the isocyanate ingredient last. The mixture was castable and cured at room temperature to a rigid polyurethane syntactic foam which did not burn, in that no burning occured after the flame was removed.
Example 3 (A) A mixture of 100 parts by weight of a commercial organic polyol (Voranol 370, trademarked and sold by Dow Chemical Company), 75 parts by weight of tris(betachloroethyl)-phosphate, 35 parts by ~eight of glass microballoons, 1.5parts by weight of a silicone surfactant and 1.0 part by weight of a mixture of one part by weight triethylene diamine and two parts by weight dipropylene glycol was prepared. To this mixture, 100 parts by weight polymethylene polyphenyldiisocyanate was added and the mixture was allowed to cure in a test sample.
(B) ~ mixture was prepared as described in (A) above except 5 parts by weight of chopped glass fiber strands o about 6 mm in length were pre~ent in the mixture~

~ 7 ....

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(C) A mixture was prepared as described in (A) abo~e except 10 parts by weight o~ chopped glass ~iber strands of about 6 mm in length were present in the mixture.
The ~lexural strength was determined on each cured sample of (h), (B) and (C) in accordance with the procedure ASTM-D-790 with the results as shown in the Table below in kilopascals (kPa).

Table Com~ tion Flexural Strength~ kPa (A) 6674 (B) 7584 (C) 9067 3o

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A rigid polyurethane syntactic foam consisting of a cured product obtained from a mixture consisting essentially of the composition obtained by mixing an organic polyol, a polyisocyanate, microballoons, a catalyst for the reaction between the organic polyol and polyisocyanate, and a substantially colorless, compatible flame retardant having a viscosity less than 100 centipoise at 24°C., having a volatility such that the flame retardant does not evaporate from the exotherm generated by reacting ingredients and said flame retardant is non-reactive in the mixture to the extent that the physical properties of the foam are not substantially changed compared to the physical properties of the foam without the flame retardant present, a combination of the organic polyol and the polyisocyanate being a liquid at 25°C., there being present in the mixture a sufficient amount of microballoons to provide a non-castable mixture in the absence of the flame retardant and the amount of flame retardant present in the mixture being sufficient to provide a castable mixture which will flow in a mold cavity to the extent that mold details are filled, and the mixture cures to a rigid polyurethane syntactic foam which is flame retardant.
2. The rigid polyurethane syntactic foam according to claim 1 in which the mixture additionally contains noncombustible flexible fibers of less than 25 mm in length.
CA251,056A 1975-09-18 1976-04-26 Flame retardant rigid polyurethane syntactic foam Expired CA1065530A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US61446575A 1975-09-18 1975-09-18
US05/662,384 US4082702A (en) 1975-09-18 1976-03-01 Flame retardant rigid polyurethane syntactic foam

Publications (1)

Publication Number Publication Date
CA1065530A true CA1065530A (en) 1979-10-30

Family

ID=27087255

Family Applications (1)

Application Number Title Priority Date Filing Date
CA251,056A Expired CA1065530A (en) 1975-09-18 1976-04-26 Flame retardant rigid polyurethane syntactic foam

Country Status (6)

Country Link
JP (1) JPS5857457B2 (en)
CA (1) CA1065530A (en)
DE (1) DE2620060A1 (en)
FR (1) FR2324665A1 (en)
GB (1) GB1528288A (en)
IT (1) IT1063359B (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2713984A1 (en) * 1977-03-30 1978-10-05 Bayer Ag STORAGE MOLDING
FR2586215B1 (en) * 1985-08-13 1988-09-02 Hutchinson THERMAL INSULATION MATERIAL OF THE SYNTACTIC TYPE, MACHINE AND METHOD FOR THE PRODUCTION THEREOF, AND INSULATION MEANS COMPRISING SUCH A MATERIAL
JPS6295318A (en) * 1985-10-22 1987-05-01 Teijin Ltd Production of polyester
US5017629A (en) * 1989-03-31 1991-05-21 The B F Goodrich Company Moldable low density thermoplastic composite with hollow glass spheres and the method for compounding
US5032627A (en) * 1989-03-31 1991-07-16 The B. F. Goodrich Company Method for reducing hollow glass sphere fracture in thermoplastic resin by melt or bulk polymerization/extrusion

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2577281A (en) * 1948-10-15 1951-12-04 Lockheed Aircraft Corp Flame retardant cellular plastic material
FR1349510A (en) * 1962-01-11 1964-01-17 Dunlop Sa Manufacturing process of elastic cellular materials and products obtained by this process
JPS4840860A (en) * 1971-09-23 1973-06-15

Also Published As

Publication number Publication date
JPS5236156A (en) 1977-03-19
JPS5857457B2 (en) 1983-12-20
IT1063359B (en) 1985-02-11
DE2620060A1 (en) 1977-03-31
FR2324665A1 (en) 1977-04-15
GB1528288A (en) 1978-10-11
FR2324665B1 (en) 1979-06-29

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Legal Events

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MKEX Expiry

Effective date: 19961030